Back for a seating unit



FIG. 1 is a perspective view of a back for a seating unit showing our new design;

FIG. 2 is an enlarged left side view thereof, the right side being a mirror image;

FIG. 3 is a front view thereof;

FIG. 4 is a back view thereof; and,

FIG. 5 is a top view thereof. 

The ornamental design for a back for a seating unit, as shown and described. 